LOW INFECTION AND NON-UNION RATES IN POLYTRAUMA FEMORAL FRACTURES: A RETROSPECTIVE STUDY

ABSTRACT Objective: Assess complications and risks in staged femoral shaft fracture treatment using external fixation and intramedullary nailing (DCO). Methods: Analysis involved 37 patients with 40 fractures, mostly male (87.5%), average age 32.9 years. Data included ASA score, AO/OTA and Gustilo classifications, Glasgow Coma Score, Injury Severity Score, times to external fixation and conversion, ICU duration, nail type, and reaming status. Complications tracked were mortality, deep infection, and non-union. Results: Predominant fracture type was AO/OTA A (45%), with 40% open (Gustilo A, 93.8%). Average ISS was 21; GCS was 12.7. Median ICU stay was 3 days; average time to conversion was 10.2 days. Retrograde nails were used in 50% of cases, with reaming in 67.5%. Complications included deep infections in 5% and non-union in 2.5%. Conclusion: DCO strategy resulted in low infection and non-union rates, associated with lower GCS and longer ICU stays. Level of Evidence III; Retrospective Cohort Study.


INTRODUCTION
Polytraumatized patients often experience a systemic immunologic response due to their multiple injuries and associated hemorrhagic shock.When this response is not well-balanced, it can lead to acute complications, including respiratory distress syndrome and multiple organ failure.1,2 Among the factors that significantly impact the clinical course of these patients, major fractures, particularly femoral shaft fractures, stand out due to their potential for causing substantial bleeding and soft tissue damage.The decision regarding how to stabilize femoral shaft fractures in polytraumatized patients is of paramount importance, as it can influence the final outcome.Early intramedullary nailing is the preferred approach for hemodynamically stable patients with good physiological reserves.In cases involving borderline hemodynamic stability or patients with limited physiological reserves, rapid stabilization using an external fixator, known as Damage Control Orthopedics (DCO), is an essential lifesaving measure that can also improve functional outcomes.3,4 However, the initial use of external fixation before definitive intramedullary nailing poses a potential risk of increased fracture complications, such as deep infections and non-union.The objective of this retrospective study is to analyze the complication rate and identify the risk factors associated with femoral shaft fractures in polytraumatized patients who were initially treated with DCO (external fixation) and subsequently underwent intramedullary fixation.By investigating these complications and their contributing factors, we aim to provide valuable insights that can inform clinical decision-making and enhance patient care in this challenging population.

CASUISTIC AND METHODS
This retrospective study has been performed at an urban university-based level one trauma center, between January 2019 and December 2021.Data were collected through a retrospective chart review and review of existing radiographs.Ethical approval was provided by the Scientific and Ethical Committee of the University under the protocol 12091.Written informed consent was obtained from all patients.The inclusion criteria were as follows: age between 18 and 65 years, with femoral shaft fracture, Injury Severity Score (ISS) ≥ 16, 5  Regarding the treatment the data collected were time to the external fixation, time to the definitive fixation, number of days in the intensive care unit (ICU), time with mechanical ventilation, respiratory complications (pneumonia, thromboembolism and acute respiratory distress syndrome), total days in the hospital, type of intramedullary nail, reamed or unreamed, post-operative infection, non-union and mortality.Infection was defined according to the fracture-related infection criteria published by Metzemakers et al in 2018, 8 and non-union was defined if the fracture was not healed within 6 months of follow-up.The qualitative parameters assessed were described for all patients using absolute and relative frequencies and the quantitative characteristics were described using summary measures (mean and standard deviation or median and quartiles).The occurrence of infection, non-union and poor outcomes (infection or non-union) were described according to the qualitative characteristics using absolute and relative frequencies and verified the association using Fisher's exact tests or likelihood ratio tests, the quantitative characteristics were described according to each outcome using summary measures and compared using Student's t-tests or Mann-Whitney tests according to the normality distribution of the data evaluated using Kolmogorov-Smirnov tests. 9 The IBM-SPSS for Windows version 22.0 software was used to perform the analyzes and Microsoft Excel 2013 software was used to tabulate the data and make the graphs.The tests were performed with a significance level of 5%.

RESULTS
During the observation period spanning from 2019 to 2021, a total of 37 patients presented with 40 femoral shaft fractures, all of which met the criterion of an Injury Severity Score (ISS) ≥ 16.These patients initially received damage control orthopedic treatment followed by definitive fixation with an intramedullary nail.Among the 37 patients included in this study, 35 (87.5%) were male, with an average age of 32.9 ± 9.4 years.Notably, three patients exhibited bilateral fractures, resulting in a total of 40 femoral shaft fractures.(Table 1) The average Body Mass Index (BMI) among the participants was 26.6 ± 4 Kg/m², with only 8 individuals (20%) being smokers.The American Society of Anesthesiology (ASA) score distribution was as follows: ASA I in 24 patients (60%), ASA II in 14 patients (35%), and ASA III in 2 patients (5%).Ten patients (25%) had associated comorbidities.(Table 1) Regarding the location of the fractures, 22 (55%) were on the right side, and 3 (8.1%)were bilateral.In accordance with the AO/OTA classification, 18 (45%) were classified as type A, 14 (35%) as type B, and 8 (20%) as type C.Among the 40 fractures, 16 (40%) were open; within this subset, 15 (93.8%) were categorized as Gustilo type A, and 1 (6.3%) as type B. The fractures were situated in the mid-portion of the shaft in 27 cases (67.5%), in the distal part of the shaft in 7 cases (17.5%), and in the distal shaft in 6 cases (15%).(Table 1) The mean Injury Severity Score (ISS) was 21, ranging from 16 to 50.The average Glasgow Coma Score (GCS) was 12.7 ± 4.1, and the mean lactate level upon initial assessment in primary care was 32.2 ± 20.2 mmol/L.(Table 1) The median duration of stay in the Intensive Care Unit (ICU) was 3 days, ranging from zero to seven days.Among the 40 patients, 13 (32.5%)required mechanical ventilation, with an average duration of 2.8 ± 2.9 days.Total hospitalization duration ranged from 9 to 58 Regarding non-union, statistical analyses indicated a correlation with a lower Glasgow Coma Score (p = 0.041) and an extended duration of stay in the ICU (p = 0.023).However, no significant correlations were observed between non-union and reaming (p = 0.242) or the type of nail employed (p = 0.452).

DISCUSSION
Polytrauma constitutes a multifaceted and potentially life-threatening condition, necessitating a comprehensive and integrated approach.Traumatic injuries affecting the head, chest, abdomen, or pelvis often carry significant physiological repercussions.When coupled with a femoral shaft fracture, these cases become even more intricate due to soft tissue damage, hemorrhage, and the ensuing systemic inflammation, which elevate the risk of complications such as pulmonary infections, thromboembolic events, morbidity, and mortality.10,11 It is noteworthy that the presence of associated injuries escalates the 30-day mortality rate, reaching 12.8% when multiple injuries are present.12 In an effort to mitigate the exacerbation of the patient's systemic condition, damage control orthopedics (DCO) is employed as an effective strategy.DCO involves the initial application of external fixation for femoral shaft fractures, followed by definitive fixation once the patient's overall systemic condition, particularly the respiratory aspect, stabilizes.This approach has demonstrated its merit in reducing both morbidity and mortality.[13][14][15][16] Our study corroborates the safety and efficacy of DCO in the management of polytraumatized patients with femoral shaft fractures.Importantly, none of the 37 patients in our cohort experienced mortality.However, it is crucial to recognize that while external fixation serves as an effective primary intervention, its continued application as the definitive treatment is not without risks and potential complications.These include loss of stability, mal-union, pin-track infections, and non-union.17 To mitigate these complications, the conversion to intramedullary fixation is recommended, 18,19 A primary concern when transitioning to intramedullary nailing is the risk of infection.This risk is compounded by the presence of Schanz screws traversing soft tissues and breaching the cortex, thereby exposing the medullary canal to the external environment.Prolonged external fixation durations, in particular, elevate the risk of infection, as the trajectory of the Schanz screw may become susceptible to pin-track infection.17 Notably, while much literature emphasizes the life-saving benefits of DCO, there is a paucity of recent research focused on the long-term outcomes and complications in patients treated with this approach, especially in the context of femoral shaft fractures initially managed with external fixation and subsequently converted to intramedullary nailing.In our study, three fractures (7.5%) developed deep infections, and notably, this did not correlate with several variables, including BMI, open fracture status, type of nail, reaming, or time to definitive fixation.Of significance is the lack of correlation between deep infection (Table 3) and the time to definitive fixation, which averaged 13 days in this subgroup.Comparatively, the rate of deep infection in closed femoral shaft fractures among non-polytrauma patients without a staged treatment approach has been reported as low in previous studies: 1% by Wolinsky  The staged treatment with conversion of external fixation to internal fixation with intramedullary nailing has historically shown higher infection rate: Taeger et al. 6.6%, 25 Malik et al., 26 and Parekh et al 16%.27 Our findings further suggest that prolonged time for conversion may elevate the risk of infection, aligning with recommendations to keep the conversion period under two weeks.28 In our series, 2 fractures (5%) resulted in non-union, with correlations identified between non-union and lower GCS, longer ICU stays, and marginally with the time to conversion.These observations challenge the notion that cranial trauma promotes bone formation and subsequent healing.Importantly, we found no correlation between non-union and the type of nail or the reaming process.(Table 4) Our non-union rate is consistent with rates reported in previous studies: 3% shown by Nowotarski et    27  However, it is essential to acknowledge the inherent limitations in our study, including the relatively small sample size and the retrospective nature of data collection, which may introduce bias and imprecision.The absence of a control group for comparison further underscores the need for cautious interpretation of our results.
In conclusion, our study underscores the life-saving benefits of DCO in polytrauma patients with femoral shaft fractures.The conversion to internal fixation with intramedullary nailing emerges as a safe strategy, characterized by low infection and non-union rates.Nevertheless, the limitations inherent to our study, including its small sample size and retrospective design, necessitate the exercise of caution in interpreting and generalizing our findings.Further research, incorporating larger cohorts and prospective methodologies, is warranted to validate and refine our observations and treatment protocols.

CONCLUSIONS
In our series the indication of damage control orthopedics in patients with femoral shaft fracture and ISS ≥ 16 lead to zero mortality.The conversion from the external fixation to the intramedullary nailing, done in average after 10 days, hasn't shown increase in infection and non-union rate.Non-union had correlation with lower GCS and longer stay in the ICU.

Table 1 .
Demographic characteristics of the patients.days,withanaverage of 35.4 ± 29.9 days.Respiratory complications, including pneumonia, thromboembolism, and acute respiratory distress syndrome, were observed in 20 patients (50%).(Table2)Theaveragetimeinterval between external fixation and intramedullary nailing was 10.2 ± 4.5 days, with a range of 3 to 24 days.All procedures were performed as one-stage interventions, involving the removal of the external fixator and subsequent fixation with an intramedullary nail.Among the 40 fractures, retrograde nails were utilized in 20 cases (50%), antegrade nails in 15 cases (37.5%), and cephalomedullary nails in 5 cases (12.5%).Reaming was performed in 27 fractures (67.5%).(Table2)Deepinfection was observed in two cases (5%), and non-union was identified in one case (2.5%) during the six-month follow-up.Notably, the latter case occurred in a patient who experienced paraplegia subsequent to a spinal cord injury.One fracture (2.5%) exhibited both deep infection and non-union.(Table2)Statistical analyses revealed that none of the patient or fracture characteristics exhibited a significant correlation with infection (p < 0.05).Furthermore, the time elapsed from external fixation to intramedullary nailing, although averaging 10 days, did not correlate significantly with the incidence of deep infection (p = 0.492).
al., 29 6% by Malik et al. 26 and 9% by Parekh et al. 27 Due the tight inclusion criteria of polytraumatized patient with ISS ≥ 16 with femoral shaft fracture treated initially with DCO the number of patients in our study was 37. Other studies also have